Hi Cristina,
those small b-value variations are fine. What you get are the b-values calculated after taking into account the effects of the imaging (i.e., non diffusion encoding gradients).
All the FSL diffusion tools will work fine with those.
Cheers,
Matteo
> On 26 Sep 2017, at 18:46, C. Roman <[log in to unmask]> wrote:
>
> Hi FSL Community,
>
> I am currently collecting multi-shell diffusion data and our scanner is outputting effective b-values, rather than just sticking to the nominal b-value we designate. For example, for a designated b-value of 500, the bval table will show 0 500 500 500 500 505 505 500 500 495 500 495 495 0, and as my b-values get larger, too do some of the deviations. Overall, it seems like this is not something to be alarmed about (according to individuals in the field), and my data seems to run well through topup and eddy, but I wanted to reach out to see if there is anything I should take into consideration, specifically regarding the effective b-values, when running my data through FSL (e.g., probtrakx, TBSS).
>
> Thank you!
> Cristina
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